Kube going cross-platform in Randa

I’m on my way back home from the cross-platform sprint in Randa. The four days of hacking, discussing and hiking that I spent there, allowed me to get a much clearer picture of how the cross-platform story for Kube can work, and what effort we will require to get there.

We intend to ship Kube eventually on not only Linux, Windows and Mac, but also on mobile platforms like Android, so it is vital that we figure out blockers as early as possible, and keep the whole stack portable.


The first experiment was a new distribution mechanism instead of a full new platform. Fortunately Aleix Pol already learned the ropes and quickly whipped up a Flatpak definition file that resultet in a self contained Kube distribution that actually worked.

Given that we already use homegrown docker containers to achieve similar results, we will likely switch to Flatpak to build git snapshots for early adopters and people participating in the development process (such as designers).


Anreas Cord-Landwehr perpared a docker image that brings the complete cross-compiler toolchain with it, so that makes for a much smoother setup process than doing everything manually. I mostly just followed the KDE-Android documentation .

After resolving some initial issues with the Qt-Installer with Andreas (Qt has to be installed using the Gui-Installer from console as well, using some arcane configuration script that changes variables with every release…. WTF Qt), this got me quickly set up to compile the first dependencies.

Thanks to the work of Andreas, most frameworks already compile flawlessly, some other dependencies like LMDB, flatbuffers and KIMAP (which currently still depends on KIO), will require some more work though. However, I have a pretty good idea by now what will be required to get everything to build on Android, which was the point of the exercise.


I postponed the actual building of anything on Windows until I get back to my workstation, but I’ve had some good discussions about the various possibilities that we have to build for Windows.

While I was initially intrigued by using MXE to cross-compile the whole stack (I’d love not having to have a Windows VM to build packages), the simplicity of the external CMake project that Kåre Särs setup for Kate is tempting as well. The downside of MXE would be of course that we don’t get to use the native compiler, which may or may not result in performance impacts, but definitely doesn’t allow developers on Windows to work with MSVC (should we get any at some point….).

I guess some experimentation will be in order to see what works best.


Lacking an OS X machine this is also still in the theoretical realm, but we also discussed the different building techniques and how the aim must be to produce end-user installable application bundles.


As you can see there is still plenty to do, so if you feel like trying to build the stack on your favorite platform, that help would be greatly appreciated! Feel free to contact me directly, grab a task on Phabricator, or join our weekly meetings on meet.jit.si/kube (currently every Wednesday 12:00).

The time I spent in Randa showed once more how tremendously useful these sprints are to exchange knowledge. I would have had a much harder time figuring out all the various processes and issues without the help of the various experts at the sprint, so this was a nice kick-start of the cross-platform effort for Kube. So thank you Mario and team that you organized this excellent event once more, and if you can, please help keeping these Sprints happening.


Author: cmollekopf

Christian Mollekopf is an open source software enthusiast with a special interest in personal organization tools. He started to contribute actively to KDE in 2008 and currently works for Kolab Systems leading the development for the next generation desktop client.

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